Anti-tussive activity of benproperine enantiomers on citric-acid-induced cough in conscious guinea-pigs

Abstract

Abstract The anti-tussive effect of the R-(+)- and S-(-)-enantiomers of benproperine was evaluated and compared with that of the racemate on cough induced by 7.5% citric acid in conscious guineapigs. All the three compounds, intraperitoneally administered 1.5 h before the test, significantly inhibited citric-acid-induced cough. The ID50 values (effective doses for 50% inhibition) (with 95% confidence intervals) were 16.1 (9.1–28.4), 23.3 (11.2–48.6), 25.4 (11.7–55.1) mg kg−1 for the number of coughs in the 3 min of challenge, and 11.9 (5.3–26.6), 13.5 (5.6–32.4), 19.2 (12.8–28.9) mg kg−1 for the number of coughs in the 5 min immediately after the challenge, for (+)-benproperine, R-(+)-benproperine and S-(-)-benproperine, respectively. These findings suggest that the use of either enantiomer does not show any advantage over the racemate with regard to their anti-tussive effect.